US2064098A - Boiler and furnace installation - Google Patents

Description

Dec. 15, 1936. w R w D 2,064,098

BOILER AND FURNACE INSTALLATION Filed May 21, 1954 2 Sheets-Sheet l ATTORNEYS Dec. 15, 1936. w. R. WOOD V BOILER AND FURNACE INSTALLATION Filed May 21; 19:54 2 Sheets-Sheet 2- ATTORNEY! Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE BOILER AND FURNACE INSTALLATION Application May 21, 1934, Serial No. 726,678

17 Claims.

The invention is primarily directed toward the combining of boiler parts which constitute or define a furnace with a horizontal type boiler with drop section, so as to produce a high capacity installation of simple and effective design.

Another object of the invention is to provide for common circulation in an arrangement such as the above, without encountering circulation difficulties.

I am aware that it has been heretofore proposed in installations having combustion chambers defined by refractories, to partially line the refractory walls with tubes connected into the circulation of the boiler, as shown for example in the patent to John E. Bell, #1,708,862, issued April 9, 1929. The arrangement of that patent, however, can only be operated at certain ratings without encountering circulation difliculties. I am also aware that to make it possible to operate at higher ratings, it has been proposed to provide independent circulation in the arrangement of the said Bell patent, as disclosed, for instance, in patent l,964,298 issued to Kreisinger and Bell on April 10, 1934.

By my invention, I am enabled to obtain even greater capacities without circulation diificulties notwithstanding that there is common circulation for the various boiler parts. In addition, I am also enabled to properly locate the superheater so as to get the desired degree of superheat at the high capacities possible with my installation.

Another object of the invention is to provide such a high capacity installation in a simple and effective manner.

Other objects and advantages of the invention will be set forth hereinafter and will be more readily understood in connection with the description of the invention.

How the foregoing together with such other objects and advantages as may hereinafter appear or are incident to my invention are realized is illustrated in preferred form in the accompanying drawings, wherein- Fig. l is a sectional elevation of a boiler and furnace installation constructed in accordance with my invention.

Fig. 2 is a fragmentary enlarged cross section taken on the line ?.-2 of Fig. 1.

Fig. 3 is an enlarged fragmentary elevational view of the header construction illustrated in Fig. 1.

Fig. 4 is an enlarged fragmentary elevational view, partly broken out, illustrating another form of header construction.

Figs. 5, 6, and 7 illustrate other header modifications; and

Fig. 8 is a fragmentary View illustrating a modification in the downflow connection to the downof any suitable type for admitting. fuel into the 15 combustion chamber, suitable casing'structure D for the installation, and structural work E from which the boiler and associated parts are sus.- pended by means of hangers and brackets, as clearly illustrated in Fig. 1. V

The boiler proper A, is of ,the horizontally inclined tube type, and in this instance comprises two spaced sections or banks of horizontally inclined tubes 9 and lo, the tubes 9 of the upper bank or section being connected at their lower ends into a plurality of downtake or downcomer headers II, and at their upper ends into a plurality of uptake or upcomer headers l2, and the tubes l 0 of the lower bank or drop section being similarly connected into a plurality of downcom'er headers l3 and upcomer headers l4.

As illustrated in Fig. 2,1the boiler tubes are arranged in staggered relation in spacing such as will give the gas flow needed for efficient heat transfer and the headers are of the sinuous type to accommodate the tubes. However, in instances where the tubes are not staggered, straight headers may be employed in place ofsuch sinuous headers. I

The downcomer headers ll of the upper bank of tubes 9, are connected to the water space of the upper steam and water drum [5 of the boiler by means of a plurality of rows of downcomer tubes or nipples I6, and these headers l l are con: nectedto the downcomer headers 13 of the lower bank of tubes ID by means of a plurality of rows of tubes or nipples IT. The upcomer headers I4 of the lower bank of tubes are connected to the upcomer headers l2 of the upper bank of tubes by means of a plurality of rows of tubes or nipples l8, and the upper headers I2 are connected to the steam space. of the drum l5 by means of a plurality of rows of delivery tubes I9. The connecting means illustrated in the form of double rows of nipples l6, l1 and [8 have a free area therethrough fairly closely approximating that through the headers so that restriction to flow is minimized. Also, the number of delivery tubes I9 is such as to provide free flow. This is particularly desirable with boilers operating under high pressures such as 1200-l400 pounds per sq. in. since in such boilers the nipples are made of smaller diameter so as to have a tube wall thickness which may be satisfactorily rolled. Likewise, as pressures rise a relatively greater downcomer and riser area is necessary in order to maintain the same fraction steam by volume leaving the steaming tubes, such as the water wall tubes, for as the pressure rises the density of the steam rises and a greater weight of steam and water mixture issues from the water wall tubes. A greater weight of steam and water mixture in the wall tubes means a relatively greater volume of water entering the tubes with resultant higher velocities and velocity heads within the wall tubes and downcomers, resulting in greater losses in circulation. These losses must then be offset by increased riser and/or downcomer areas and as pointed out above, I accomplish this by increasing the nipple areas.

The furnace or combustion chamber B is defined by steam evaporating tubes, the front wall being defined by a row of closely spaced upright tubes 20, the rear wall by a row of closely spaced tubes 2|, and each of the side walls by a row of closely spaced tubes 22. These parts, in effect, constitute a. furnace-shaped boiler. At the top of the combustion chamber, a row of tubes 23 is provided in advance of the lower bank of tubes 9 of the boiler to minimize clogging of the gas passage of said bank, and at the bottom, a row of tubes 24 is provided, the spacing being such as to permit gravitating particles to fall through to the ash pit below.

The front wall tubes 20 are connected at their lower ends into a lower drum or header 25, and at their upper ends into an upper header 26, and the rear wall tubes 2I are connected at their lower ends into a lower header 21 and at their upper ends into an upper header 28. The bottom tubes 24 are connected at one end into the drum or header 25 and at the other end into the header 21, and the top tubes 23 are connected at one end into the header 25 and at the other end into the header 28. The header 28 is connected to the uptake headers Id of the boiler A by means of nipples 35.

The tubes 22 of the side walls are connected at their lower ends into lower headers 29, which in turn are connected to the lower drum or header 25 by means of a plurality of supply tubes 30, and these side wall tubes are connected at their upper ends into upper headers 3| which in turn are connected to the steam space of the drum I5 by means of a plurality of delivery tubes 32.

It is to be noted that the upper headers 3I of the side Walls are located at the upper portion of the boiler A and that the side wall tubes 22 preferably extend for the full height of the installation.

Water is supplied to the lower drum or header 25 by means of a plurality of downcomer tubes 33, located within the casing D and extending downwardly from the lower headers I3 of the boiler, and since all of the steam evaporating tubes referred to have connection with the drum 25, it serves as a common supply means therefor.

The drum 25, due to its low location and to the particular connections of the boiler and steam evaporating tubes thereto, serves as a common blowdown or drain for the entire unit, a Su table blow-off valve 34 being provided for this purpose.

It will be seen from the foregoing that the arrangement described is one. calculated togive very high capacities, assuming that there are no circulation difiiculties and that too much water is not carried into the steam and water drum.

I have discovered that if I increase the nipple area in the boiler A, I provide for adequate circulation, and that the recirculation occurring in the main bank of tubes 9 prevents the carrying over of too much water into the drum I5, as will further be described.

The headers of the boiler A as illustrated in Figs. 1, 2, and 3, may be of standard width and depth, the standard depth in an installation of the proportions illustrated being 6" as indicated by the dimension line a in Fig. 3. The tubes or nipples I3, II, I8, and 35 are preferably 3 /2" in diameter and therefore, since the headers are only 6" in depth, I increase the depth at their end portions where the nipples are secured thereto, as indicated at IBa, Ho, and I 8a, so as to obtain sufficient area for accommodating the double row of nipples with proper ligament strength. These enlarged ends may be provided by welding portions I8b to the headers, as illustrated in Fig. 3.

Referring to Fig. 1, the circulation in the boiler A is from the drum I5 downwardly through the tubes or nipples I5 to the headers II, and downwardly therefrom through the nipples I! to the headers I3. Flow is then upward through lower rows of the tubes 9 of the upper bank and through the tubes I0 of the lower bank to the connected upcomer headers I2 and I I, and thence from the upper headers I2 to the steam space of the drum I5 by means of the delivery tubes I9.

The circulation in the steam evaporating tubes of the furnace is downwardly from the headers I3 through the downcomer tubes 33 to the drum or header 25. Circulation from the drum 25 is upwardly through the front wall tubes 20 and top tubes 23 to the header 23 and also upwardly through the bottom tubes 24 and rear wall tubes 2i to the header 28. From this header flow is upwardlythrough the nipples 35 and the connected boiler headers I2 and I4, and from thence to the steam space of the drum I5 through means of the delivery tubes I9. The side wall tubes 22 receive water from the lower drum 25 by means of the tubes 30 and deliver into the steam space of the upper drum I5 by means of the tubes 32.

In connection with the circulation, it is pointed out that since the tubes I0, the tubes 2|, and the tubes 20 and 23 deliver into the headers I4, and since these headers in turn deliver into the headers I2 into which also the tubes 9 deliver, it would normally be expected that there would be so much water in the mixture in the headers I2 that too much water would be carried into the drum I5; particularly since the circulation through the tubes 20, 2i and 23 is relatively very rapid, producing a tendency to elevate water in the headers I2. I have found, however, that the recirculation which occurs in the main or upper bank of tubes overcomes this difiiculty, there be ing a substantial downflow through the upper rows of the tubes of this bank. The amount of recirculation occurring in the main bank is somewhat dependent upon the number of rows of tubes employed in such bank. The requisite number can be readily determined for any given installation. In the drawings, the main bank is fourteen rows of tubes high.

As will be seen from Fig. l, I locate a superheater S in the vertical space between the upper and lower tube banks so that it is in a location where the desired degree of superheat will be obtained. I am enabled to so locate the superheater because of employing a drop section in the boiler connected to the upper section by means such as the nipples spaced apart sufficiently to permit of insertion and removal of the superheater tubes. In this connection it will be noted that there are only a few rows of tubes in the lower bank for the reason that the radiant heat tubes of the combustion chamber absorb a large quantity of heat, which makes it advantageous to locate the superheater as shown.

In Fig. 4, I have illustrated a modification in which in addition to providing increased nipple area, I also provide increased header area by enlarging the headers. In instances where the size and spacing of the tubes of the boiler, in order to secure efficient heat transfer in the boiler, is such that increased header area cannot be obtained by increasing the width of the headers, I obtain the extra area by increasing the depth of the headers, in which case, as shown in Fig. 4, ample area is provided for the double row of connecting nipples. In high pressure boilers where smaller tubes are employed narrower headers than standard may be used to give closer tube spacing and the extra area may be obtained by making the headers of greater depth. While I have only illustrated the downcomer headers Ila and |3a in Fig. 4, it will be understood the upcomer headers may be of similar construction.

The construction of the headers of. the boiler A, as shown in Figs. 5 to? inclusive, differs from that of the other figures in that interior partitions or dividing walls are employed. As illustrated in Fig. 5, the headers are divided into inner and outer separated compartments or chambers 39 and 40 by the partitions 4|. At the upper portion of the upper headers I2, I provide cross portion 43 (see Fig. 9) so that the chambers 39 deliver to the lower rows of tubes l9 and the chambers 49 to the upper rows. As illustrated in Fig. 6, the partitions are provided with apertures in line with the tubes and with the apertures in the outer walls of the header for inserting and securing the tubes in place. These aper tures are provided with closures such as plugs 42.

In the modifications illustrated in'Fig. 6 and '7, I employ cross partitions 44 in the inner chambers 39 of the headers l3 and M of the lower bank of tubes l0. These cross partitions are located directly above the lowermost row of tubes of the bank l9, and the lower portions of the upright or dividing partitions 4| of the upcomer headers M are cut away so that the tubes of the bottom row communicate with the outer chambers 40 of the headers. At the downcomer headers 13, however, the upright partitions 4| extend for the full height of the headers. It will be seen that in this arrangement, therefore, the front wall tubes 20 are connected with the lower row of tubes of the bank In, and that these in turn deliver into the outer chambers M! of the upcomer headers 14, from which delivery is to the steam and water drum.

In some instances, it may be desirable to construct the upcomer headers M as shown in Fig. 5, and the downcomer headers as shown in Fig. '7, in which case the front wall tubes 20 would 'deliver into the inner chambers 39 of the upcomer headers l4 through the medium of the bottom row of tubes of the bank [-0, and the bottom tubes 24, and the rear wall tubes 1| would deliver into the outer chamber 40 of said upcomer headers.

In the modification illustrated in Fig. 8, I have shown the downcomer tubes IBa as being of a capacity sufliciently large to adequately supply both the boiler A and the wall tubes.

The various headers may be of .welded construction with the dividing partitions welded in place, or they may be one piece with the'partitions in the form of plain strips dropped in through an open top.

It is pointed out that the divided headers are particularly useful where the water walls are of. relatively low height in which case segregation of the column of steam-water mixture rising from the walls to the steam and water drum of the boiler, is desirable in order to maintain a light column of mixture in the risers to the drum so as to stimulate the wall circulation.

Assuming that the tubes of the boiler banks are 4 inches in diameter, the tubes of a horizontal row would be spaced apart approximately 7 inches and the rows of tubes from centre line to centre vertically considered would be spaced apart approximately Gf ths inches.

It is to be observed that through the practice of my invention, an installation of very simplified character is provided because the downcomer tubes 33 and the rear wall tubes 2| may be aligned with the headers of the boiler A while still providing effective circulation in the system. These tubes as well as the side wall tubes and in fact all of the connections referred to, are all located within the casing D which provides a very compact arrangement and permits of great plainness and simplicity of the casing. Furthermore, I obtain through my arrangement, the advantages of effective circulation throughout the system without the necessity of employing the customary complicated arrangement of tubes located outside the casing, it being noted that there are no outside downcomers or upcomers and that the downcomer tubes 33 and front wall tubes 20 are located in a common wall of. the casing.

In explanation of the above, it is pointed out that while arrangement such as shown in the above mentioned Kreisinger and Bell patent avoid circulation difficulties, the number of tubes required as downcomers and upcomers greatly increases the cost of the installation and also presents difficulties in the design, because most of them have to be located outside of the boiler and furnace setting where they interfere with access doors, structural members of thesetting, burner or stoker parts, and the like. In addition, in such arrangements, many of the tubes have to be bent for the most part with individualbends, which of course, adds materially to the cost as do the complications arising in connection with the propersh-eathing of. the tubes.

I claim: a

1. The combination with a boiler having an upper and a drop tube section each comprising a plurality of horizontally inclined tubes and downcomer and upcomer headers into which the tubes are connected, of a combustion chamber associated with said boiler, steam evaporating tubes in the chamber constituting walls of the combustion space thereof, downcomer means connecting said steam evaporating tubes to the boiler for supply, said steam evaporating tubes being connected to deliver into the upcomer headers of the drop section of the boiler, and means connecting said upcomer headers to the upcomer headers of the upper section having a free area therethrough approximating that through the headers whereby to minimize restriction to flow.

2. The combination with a boiler having an upper and a drop tube section each comprising a plurality of horizontally inclined tubes and downcomer and upcomer headers into which the tubes are connected, of a combustion chamber associated with said boiler, steam evaporating tubes in the chamber constituting walls of the combustion space thereof, downcomer means connecting said steam evaporating tubes to the boiler for supply, said steam evaporating tubes being connected to deliver into the upcomer headers of the drop section of the boiler, and means connecting the said upcomer headers to the upcomer headers of the upper section, said connecting means having a cross-sectional area approximating the cross-sectional area of the upcomer headers whereby to provide free delivery from the tubes of the drop section and from the steam evaporating tubes into said upcomer headers of the drop section, and from said upcomer headers of the drop section to the upcomer headers of the upper section.

3. The combination with a boiler having an upper and a drop tubesection each comprising a plurality of horizontally inclined tubes and downcomer and upcomer headers into which the tubes are connected, of a combustion chamber associated with said boiler, steam evaporating tubes in the chamber constituting walls of the combustion space thereof, downcomer means connecting said steam evaporating tubes to the boiler for supply, said steam evaporating tubes being connected to deliver into the upcomer headers of the drop section of the boiler, and a plurality of means connecting said upcomer headers of the drop section to the upcomer headers of the upper section, said connecting means having a crosssectional area approximating the cross-sectional area of the upcomer headers whereby to provide free delivery from the tubes of the drop section and from the steam evaporating tubes into said upcomer headers of the drop section, and from said upcomer headers of the drop section to the upcomer headers of the upper section, said connecting means being spaced apart to permit removal of superheater tubes therebetween, and a superheater in the space between sections.

4. The combination with a boiler having an upper and a drop section each comprising a plurality of horizontally inclined tubes and downcomer and upcomer headers into which the tubes are connected, of a combustion chamber associated with said boiler, steam evaporating tubes in the chamber constituting walls of the combustion space thereof, said steam evaporating tubes having downcomer and upcomer connection to the downcomer and upcomer headers respectively of the drop section, and means connecting the headers of the drop section to the headers of the upper section having a free area therethrough approximating that through the headers whereby to minimize restriction to flow.

5. The combination with a boiler having an upper and a drop section each comprising a plurality of horizontally inclined tubes and downcomer and upcomer headers into which the tubes are connected, of a combustion chamber associated with said boiler, steam evaporating tubes in the chamber constituting walls of the combustion space thereof, said steam evaporating tubes having downcomer and upcomer connection to the downcomer and upcomer headers respectively of the drop section, and double rows of nipples connecting the headers of the drop section to the headers of the upper section.

6. In a high capacity boiler and furnace installation the combination of a boiler of the horizontally inclined tube type and a furnace having steam evaporating tubes constituting walls of the combustion space thereof, said boiler having an upper section and a drop section each comprised of upright downcomer and upcomer headers, and horizontally inclined tubes connecting the headers, a plurality of rows of nipples connecting the upcomer and downcomer headers of the sections together, and downcomer means leading from the downcomer headers of the drop section to said steam evaporating tubes, said steam evaporating tubes being connected for delivery into the upcomer headers of the drop section.

'7. The combination with a boiler having a steam and water drum, an upper tube section, a drop tube section therebelow, each section comprising a plurality of horizontally inclined tubes and downcomer and upcomer headers into which the tubes are connected, of a combustion chamber associated with said boiler, steam evaporating tubes in the chamber constituting walls of the combustion space thereof, downcomer means connecting said steam evaporating tubes to the downcomer headers of the drop section for supply, said steam evaporating tubes being connected to deliver into the upcomer headers of the drop section, means connecting the downcomer headers and the upcomer headers of the sections together, having a free area therethrough approximating that through the headers, downcomer means from the water space of the steam and water drum to the downcomer headers of the upper section, having a free area therethrough approximating that through the headers, and a plurality of delivery tubes leading from the upcomer headers of the upper section to the steam and water drum, said delivery tubes having a combined free area approximating the cross-sectional area of said upcomer headers to provide free delivery to the drum; whereby to minimize restriction to flow.

8. The combination with a boiler having a steam and water drum, a plurality of substantially horizontal tubes, and downcomer and upcomer headers into which the tubes are connected, of a combustion chamber associated with said boiler, and steam evaporating tubes defining the upright walls of the combustion chamber, all of said steam evaporating tubes having downcomer connection with said downcomer headers of the boiler, and the steam evaporating tubes of at least two of said walls having upcomer connection with said upcomer headers of the boiler, and said headers being of a capacity greater than necessary to provide effective circulation in such boiler, the excess capacity being such as to provide eifective circulation in the steam evaporating tubes without interfering with the boiler circulation, the remaining of said steam evaporating tubes being connected for delivery to said steam and water drum.

9. In a high capacity boiler and furnace installation, the combination of a boiler of the horizontally inclined tube type and a furnace having steam evaporating tubes lining its upright walls, said boiler having a steam and water drum, a plurality of upright downcomer and upcomer headers, and horizontally inclined tubes of standard spacing connected at their ends into said headers, downcomer means leading from the downcomer headers of the boiler to said steam evaporating tubes, the steam evaporating tubes of a pair of opposite walls being connected for delivery into said upcomer headers, and the upcomer headers being of standard Width to accommodate the standardly spaced boiler tubes, but of a depth considerably greater than standard, whereby the circulation of the boiler and-of the steam evaporating tubes is adequately provided for without interference of one with the other, and the tubes of the remaining pair of opposite walls being connected for delivery to the steam and water drum.

10. In a high capacity boiler and furnace installation, the combination of a boiler having horizontally inclined boiler tubes and a plurality of upright downcomer and upcomer headers into which said boiler tubes are connected, and a combustion chamber below said boiler having upright steam evaporating tubes at a wall thereof, upright downcomer tubes leading from said down-- comer headers and connected to supply said steam evaporating tubes, said downcomer tubes and steam evaporating tubes being arranged in rows in close parallel relationship and in approximate alignment with said downcomer headers, means connecting said steam evaporating tubes to deliver into the upcomer headers of the boiler, upright steam evaporating tubes at the opposite wall of the combustion chamber in alignment and delivery connection with said upcomer headers, and means connecting said last mentioned wall tubes to receive Water supply from the boiler.

11. In a high capacity boiler and furnace installation, the combination of a boiler having horizontally inclined boiler tubes and a plurality lationship and in approximate alignment with said downcomer headers, means connecting said steam evaporating tubes to deliver into the upcomer headers of the boiler, upright steam evaporating tubes at the opposite wall of the combustion chamber in alignment and in delivery connection with said upcomer headers, a lower header into which the lower ends of the said last mentioned tubes are connected, and tubes extending across the lower portion of the combustion chamber connecting the first mentioned header means and said second mentioned lower header.

12. In a high capacity boiler and furnace installation, the combination of a boiler having horizontally inclined boiler tubes and a plurality of upright downcomer and upcomer headers into which said boiler tubes are connected, and a combustion chamber below said boiler having upright steam evaporating tubes at a wall thereof, upright downcomer tubes leading downwardly from said downcomer headers, a lower header into which the lower ends of said steam evaporating and downcomer tubes are connected, said tubes being arranged in rows in close parallel relationship and in approximate alignment with said downcomer headers, an upper header into which the upper ends of said steam evaporating tubes are connected, upright steam evaporating tubes at the opposite wall of the combustion chamber in alignment with said upcomer headers, a lower header into which the lower ends of the said last mentioned tubes are connected, spaced tubes extending across the lower portion of the combustion chamber connecting the first and second mentioned lower headers, an upper header into which theupper ends of the second mentioned steam evaporating tubes are connected, means connecting said last mentioned upper header with the upcomer headers of the boiler, and spaced tubes extending-across the upper portion of the combustion chamber connecting said first and second mentioned upper headers.

13. In a high capacity boiler and furnace installation, the combination of a boiler of the horizontally inclined tube type comprising a plurality of upright front downcomer and rear upcomer headers and horizontally inclined tubes connected at their ends into 'said headers, casing structure enclosing said boiler, a furnace below said boiler having its front and rear walls in approximate alignment with the front and rear upright headers of the boiler respectively, upright steam evaporating tubes lining said walls and exposed to the radiant heat of the furnace, downcomer tubes at and within said front wall connected to the downcomer headers of the boiler and to said wall tubes for supplying said wall tubes with water from the boiler, and said wall tubes being connected to deliver into the upcomer headers of the boiler.

14. In a high capacity boiler and furnace installation, the combination of a boiler of the horizontally inclined tube type comprising a plurality of upright front downcomer and rear upcomer headers and horizontally inclined tubes connected at their ends into said headers, casing structure enclosing said boiler, a furnace below said boiler having its front and rear walls in approximate alignment with the front and rear upright headers of the boiler respectively, upright steam evaporating tubes lining said walls and exposed to the radiant heat of the furnace, downcomer tubes at and within said front wall connected to the downcomer headers of the boiler and to said wall tubes for sup-plying said wall tubes with water from the boiler, said wall tubes being connected to deliver into the upcomer headers of the boiler, upright steam evaporating tubes lining the side walls of the furnace and exposed to the radiant heat thereof, means connecting said side wall tubes to receive water from the downcomer headers of the boiler, and means connecting said side wall tubes to deliver into the boiler, all of said tubes being confined inside the walls of the furnace and the casing of the boiler.

15. In a high capacity boiler and furnace installation, the combination of a boiler of the horizontally inclined tube type and a furnace having steam evaporating tubes ranged upright at its side, front, and rear walls, said boiler having a plurality of downcomer and upcomer headers and horizontally inclined tubes connected at their ends into said headers, and an upper steam and water drum into which the boiler tubes deliver, downcomer means leading downwardly from the downcomer headers of the boiler, means connecting said downcomer means with the lower portions of said steam evaporating tubes, the steam evaporating tubes of the front and rear walls being connected for delivery into the upcomer headers of the boiler, and means connecting the steam evaporating tubes of the side walls for delivery into the steam and water drum of the boiler.

16. In a high capacity relatively high pressure boiler and furnace installation the combination of a boiler of the horizontally inclined tube type comprising a plurality of upright front downcomer and rear upcomer headers and horizontal- 1y inclined boiler tubes connecting them, a furnace below said boiler having its front and rear walls lined with upright steam evaporating tubes, partition means dividing said downcomer boiler headers into inner and outer chambers, downcomer tubes leading from said outer chambers to said wall tubes, partition means sub-dividing said inner chambers into upper and lower chambers, and being so located that the lowermost boiler tubes connect into the lower chambers and that the remaining ones connect into the upper chambers, the partition means in said rear upcomer headers being arranged so that said lowermost boiler tubes deliver into the outer chambers of said headers, said front walltubes being connected to deliver into the bottom inner chambers of the boiler downcomer headers, and said rear nected into two circulation circuits of substantially equal resistance to flow, one of said circuits being connected for delivery to said steam and water drum and the other of said circuits being connected for delivery with said upcomer headers of the boiler.

WILFRED ROTHERY WOOD.

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